Ординатура / Офтальмология / Английские материалы / Oculoplasty and Reconstructive Surgery Made Easy_Garg,Touky, Nasralla_2009
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Congenital Nasolacrimal Duct Obstruction 139
COMPLICATIONS AND PROGNOSIS
Bleeding
Serious bleeding is rare, occurring in only 1-2% of surgeries or postoperatively.
Surgical Failures
In these complicated conditions, a 10% rate of failure occurs. Wound infections: These occur in 5-10% of patients, usually as wound abscesses on the fourth postoperative day.
Silicone or Polyethylene Tubing Complications
These complications occur in about 15% of cases and include the following: corneal abrasion, pyogenic granuloma, lowgrade infection, chronic nasal irritation and congestion, epistaxis, sinusitis, and pharyngitis.
Bypass Tube Complications
These frequently occur in at least 40% of patients postoperatively and include tube loss or migration and tube obstruction.
Anesthesia Complications
In children, these complications are more frequent due to drugs, blood loss, malignant hyperthermia, and pseudocholinesterase deficiency.
INTRODUCTION
In an ideal situation, the amount of tear output should be equal to the amount to be eliminated. Unfortunately this is not always the case, and tearing is a frequent symptom in Ophthalmology clinics. Among the various causes of tearing, primary acquired nasolacrimal duct obstruction (PANDO) is the most frequently encountered cause.
PATHOPHYSIOLOGY
The exact cause of PANDO is not known. Diverticula of the lacrimal passages, descending infection from the eye, ascending infection from the nose, abuse of topical medications, and the use of carbon based cosmetics (Kohl) have all been listed as possible etiologies.
Pathological findings in PANDO include fibrous or fibrovascular obstruction of the surrounding cavernous body and the lumen of the nasolacrimal ducts. Other interesting pathological findings include squamous metaplasia in the stenotic area, in addition to loss of goblet cells. Dacryoliths may also be found in 10-20% of patients with acquired lacrimal obstructions. They are particularly common in the lacrimal sac. Their presence is of clinical importance because contrary
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to classical lacrimal teaching, which states that the presence of positive regurge of pus from the sac means no further investigations, syringing may still be of help if the cause of the obstruction is a lacrimal stone as it may be pushed through an otherwise healthy nasolacrimal duct causing relief of the situation. Furthermore, failure to observe and remove a dacryolith during lacrimal surgery may result in recurrence.
CLINICAL EVALUATION
History
Answers to be sought include whether the tearing is on daily basis or interrupted, whether the tears are watery or viscous, whether there has been a previous history of facial swelling (acute attack). History of abuse of topical medications or systemic chemotherapy is also important as these may serve as a cause of punctal or nasolacrimal duct obstruction.
A gritty, foreign body sensation, an itching eyelid, and the absence of daily epiphora usually alert the physician to a local ocular cause for epiphora not in the lacrimal drainage system
Clinical Evaluation
The dye disappearance test (DDT) is used to determine whether the outflow system is working or not. A drop or 2 of fluorescein are placed in the conjunctival sac in both eyes regardless of whether one or both eyes are asymptomatic. The eyes are evaluated a few minutes later (Figure 1), to observe the amount of fluorescein stained tears in the conjunctival sac. A positive result is more easy to observe if obstruction is unilateral.
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Figure 1: Unilateral and bilateral positive DDT
In Lacrimal syringing, a lacrimal cannula is introduced through the canaliculus; preferably the upper. If a soft stop is encountered, this indicated canalicular obstruction, and the cannula is withdrawn and the length of patent canaliculi is measured in millimeters. If no obstruction is encountered, normal saline is irrigated through the lacrimal canaliculi. If the fluid passes immediately into the nose, the lacrimal outflow system is patent. If the fluid initially regurges through the opposite canaliculus, then passes to the nose a couple of seconds later, then a partial obstruction should be suspected. If all fluid regurges through the opposite canaliculus then PANDO should be diagnosed. If fluid regurges through the same punctum, then a canalicular obstruction is present. Figure 2 summarizes all the possible results of syringing.
Radiological Evaluation
Generally speaking, evaluation of the tearing patient is clinical not radiological. Several radiological tests are available like dacryocystography (DCG), scintillography, CT-DCG, and ultrasonography of lacrimal system may be needed in children
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Figure 2: Possible sites of acquired lacrimal obstructions. 1,2: Distal and proximal canalicular obstruction, 3: Common canalicular obstruction,
4: Nasolacrimal duct obstruction, P: Punctal stensosis, D: Dacryolith in the lacrimal sac
or in uncooperative patients who refuse office syringing. A formal computed tomography, and nasal endoscopy may be needed if there is a history of associated sinus disease or if there is a suspicion of nasal or lacrimal system neoplasia.
DIFFERENTIAL DIAGNOSIS
The most important is to differentiate other causes of tearing from PANDO. This includes : dry eyes, functional tearing due to lacrimal pump failure and secondary nasolacrimal duct obstruction as in cases of nasal pathology or old fractures
(Figures 3 to 5).
TREATMENT
Dacryocystorhinostomy or DCR is the gold standard to treat PANDO. Three different approaches exist but they all have a common goal which is to create an alternative long-term pathway for the tears by creating an epithelial lined tract
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Figure 3: Mucocele of the lacrimal sac
Figure 4: Positive resurge of pus from the sac upon digital pressure
between the lacrimal sac and the nasal mucosa. These different approaches simply differ in the route used to create the fistula. The international standard is the external transcutaneous route introduced by TOTI way back in 1904 and is still by far the most frequently performed and the most successful lacrimal procedure worldwide. Endonasal techniques; either endoscopic or non-endoscopic have been in the rise in the past 20 years, but they still suffer from several drawbacks,
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Figure 5: Canaliculitis of the upper and/or lower canaliculi should never be confused with a mucocoele, because the management is entirely different
Figure 6: EXT-DCR, skin incision designs. Care should be taken to avoid injuring the angular vein (arrows)
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Figure 7: Endonasal non-endoscopic DCR. A 20-gauge vitrectomy light probe is gently introduced through the upper canaliculus top (to) visualize the surgical site without the aid of an endoscope
Figure 8: Endoscopic view of the left nasal cavity. The endoscope allows excellent visualization of the procedure but interferes significantly with the inlet and exit of surgical instruments especially in the presence of a deviated nasal septum, or a hypertrophied middle turbinate. LNW, lateral nasal wall. MT, middle turbinate. S, Intended surgical fistula site
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Figure 9: Complete disappearance of the DCR scar one month after surgery
Figure 10: Prolapsed lacrimal tube after successful
EXT-DCR (Spaghetti sign)
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Figure 11: Pyogenic granuloma developing on top of a silastic stent
Figure 12: The Jones pyrex tube could be used as a bypass conduit of tears in case of complete punctal and canalicular stenosis